Worcester Bosch 28CDi No Hot Water

I was asked by a lady to look at her Worcester Bosch 28CDi combination boiler because her hot water performance had been gradually declining before failing altogether. The decline occurred over a couple of months and first began to affect the upstairs taps. The lady had already called another engineer who gave her a price to replace the entire diverter valve, and asked me to give her a price as we had previously done work for her.

When I arrived the lady explained everything to me and so I tested the boiler to see what was happening. I ran the hot tap and nothing happened at the boiler. From below the boiler you can see the operation of the diverter valve and differential pressure valve. As I ran the hot tap the pin was hardly moving if at all to operate the hot water micro-switch. The lady explained that the hot water did work to some extent if the central heating was on. I put the central heating on and again opened a hot tap. Still the pin was not moving to an obvious degree. I asked about the temperature of the hot water as it was barely warm and the lady told me that it only came through hot once the heating had been on for some time.

It may have been that the boiler could have been repaired by replacing just the diaphragm inside the differential pressure valve. As the hot water had not been working at all and there was no visible movement of the hot water pin I decided that it would be best to replace the whole diverter valve as this is what I had quoted to do. I had brought the relevant diverter valve with me which are relatively inexpensive and fit a number of different boilers. Fortunately the valve also came with the associated o-rings and washers to make the job run smoothly.

I turned off the water supply and drained the water system as far as possible. I turned off both the valves to the boiler on the central heating circuit after warning the lady that they may require replacement. Operating the valves on a combination boiler is something I try to avoid doing as they often begin to leak due to their in-operation over the years. I chose isolate the boiler at the flow and return valves because the boiler was on the ground floor and only 18 inches off the floor which means it was one of the lowest points of the system. I then opened the white plastic drain points on the boiler which were completely blocked. Fortunately the boiler was high enough off the floor allowing me to get a bucket underneath and use a thin screwdriver to unblock the drain points.

With the boiler drained as far as possible the first task was to remove the filling loop. There are two screws at the left hand end that secure it to the heating manifold and it just pushes in to the water differential valve and seals using an o-ring. There is a metal plate which prevents the filling loop from moving to the left and coming out from its position. Once the two screws on the left hand end of the filling loop are undone the plate can be swung down and the filling loop gently twisted to get some movement before disengaging it from its location.

The next job is to remove the plate heat exchanger, which usually contains some water still and is worth putting a towel over the pcb housing for some extra protection. There is a clip on the top right of the plate heat exchanger which is held on by a screw which need to be removed. There is also a nut which needs to be undone and secures the plate heat exchanger to the diverter valve. The other two connections are just push-fit connections sealed by o-rings. So once the nut and the clip are undone the plate heat exchanger should be eased off the other two connection with a gentle twisting motion trying not to drop too much water over the pcb housing.

Now the diverter valve should be accessible.

The diverter valve needs to be removed in one piece with the differential pressure valve. Firstly, I disconnected the copper bypass pipe connected to the plastic flow manifold. I then undone the heat exchanger connection nut to the top of the diverter valve assembly. I pulled off the circlip securing the micro-switch to the right-hand end and pushed it up out of the way. There are a number of screws to be undone, I removed all the screws for the bracket on the right-hand end and four on the plastic flow manifold. The diverter valve should now be free to come out of the boiler. This diverter valve took some persuading as it was the original, I managed to add some leverage using a large screwdriver between the rear of the boiler and the diverter valve assembly.

Re-assembly is relatively straight forward if you replace and grease all the o-ring. The most stubborn o-ring to remove was the o-ring between the plastic flow manifold and the flow isolating valve. Due to its location it was difficult to get at and remove. I managed to get a thin screwdriver underneath it and snip it with the point of my Stanley knife. Fitting the bypass pipe back into the flow manifold before securing the flow manifold is also advisable. Don't forget to fit the new filter mesh to the cold water inlet. The metal locating bracket for the filling loop also needs to be slid over the diverter valve connection before refitting the plate heat exchanger. The plate heat exchanger wasn't lined up correctly the first time I fitted it and would advise to connect the nut to the diverter valve first.

Once everything was back together, I refilled the water and heating system. Fortunately there was no leaks. I tested the operation of the hot water which was working perfectly. I then tested the heating system and checked the radiators for air. Overall the job took 2 1/2 hours and I had only allowed 2. With the experience from this job I may be able to get it down to two hours but may quote for three in the future and take my time.

Disclaimer: The works described in this blog are a record of work undertaken and should not be taken as guaranteed to solve your problem. Work should only be carried out by persons qualified and competent to do so.

What can a new Boiler give you? by Tom Key, Direct Heating Supplies

This is a guest post from Tom Key, the Online Marketing Coordinator at Direct Heating Supplies. Direct Heating Supplies are one of the UK's leading suppliers of plumbing and heating supplies.

What can a new Boiler give you?

What do you look for in a boiler? Reliability? Cost effectiveness? Durability? The good news is that a new boiler can give you all of these things and more.

An inefficient, old boiler can cause much frustration and can also cost you a lot of money to restore it to full working order.

It is highly recommended that you arrange for gas and oil boilers to be serviced on a regular basis to clarify that your boiler and corresponding heating system is working efficiently in the appropriate manner.

Having a heating engineer out to look at an older system every year can help you to ensure that your boiler is working to the highest levels of heating efficiency possible (which can contribute towards a significant financial saving) and can help you to identify and resolve any potential issues before they get out of hand.

Unfortunately there are some times when you have to face the inevitable and acknowledge that to get the best levels of heating performance you may have to move to a new boiler that can offer a massive improvement in performance.

Older boilers generally offer a less efficient performance, purely due to the improvements in technology within the heating industry.  For example, the condensing technology that operates within a modern combi boiler makes it a lot easier to recapture heat energy that is produced by the boiler but would otherwise be lost via the flue along with waste gases and condensate.

This new development means that almost all new gas Combination boilers are SEDBUK A-rated, the highest possible efficiency rating available in the UK. Around £300 a year could be saved if you made the move from an older non-condensing G-rated Combi Boiler to a new and improved condensing combi boiler. That’s an efficiency saving of around 30% - a huge improvement.

Finding a spare heating part for an older boiler becomes much trickier over time as boiler ranges become discontinued and new boilers and parts are released. New boilers need less maintenance any way but if they do the parts are always readily available

For the most part new combi boilers last upwards of 10 years, so you will soon recoup the majority of money that you have spent on a new boiler system. New boilers tend to be covered by fairly extensive boiler warranty periods too, so you have added peace of mind that if anything goes wrong with your system you are in a good position to have it sorted out.

Although an expensive purchase, the benefits of a new boiler can be cost effective and can also be well worth it in terms of relieving unwanted stress!

About this article: This article was written by Tom Key, Online Marketing Coordinator at Direct Heating Supplies for use on the Gas Central Heating Blog.

LINKS:

·         New combi boilers - http://www.directheatingsupplies.co.uk/shop/cid_1956/Gas-Combi-Boilers.aspx

·         Direct Heating Supplies - http://www.directheatingsupplies.co.uk/

Radiators Not Getting Very Hot Downstairs

I went to look at the central heating system of a lady who was complaining that the radiators downstairs were not getting very hot. When the central heating came on the radiators upstairs all got nice and hot straight away, but the radiators downstairs would take an hour before they started to get hot.

I got to the job for eight in the morning so I could see what was actually happening as the heating was set to come on at 730. I looked around the radiators downstairs and only one of the small radiators downstairs was significantly hot. The others were just lukewarm except one which was stone cold. I looked around the radiators upstairs and they were all nice and hot as expected.

Looking in the airing cupboard where the programmer was located I could see that the heating and hot water were both set to be on. I checked the motorised valve and it was in the mid position, 'M'. Being a Drayton MA1 valve there is a sticker on the side which an indicator points to show the position the valve is in. The cylinder thermostat was set to 60°C and so I turned it down and the valve moved to the 'H', central heating position.

I waited for a few minutes and gradually the radiators began to heat up downstairs including the radiator that was completely cold. It appears that the water is going through the cylinder in preference to going round the radiators downstairs. When the hot water was set to be on at the same time as the heating and the cylinder thermostat was demanding hot water the radiators wouldn't heat properly downstairs until the hot water thermostat was satisfied. I checked the settings in the programmer and could see that both the heating and hot water where set to be on from 7am until 10am but in the afternoon the hot water was set to be on 3-5pm and the heating 5-10pm. I asked the lady if she noticed that the problem had only been occurring in the morning which she said it had, but"'assumed the downstairs radiators where working because they had got up to temperature in the morning".

I set the hot water so that it would come on from 6-7am which should be enough as she lives alone and will heat quicker than if on with the central heating. If that wasn't enough on some days the timer could always be put on for an extra hour. The system is fairly old and could most definitely benefit from a powerflush. Unfortunately this is something which she cannot afford at the moment but will probably have done in the summer. It would also be prudent to fit a gate valve to the hot water cylinder return to help balance the system.

Baxi WM No Heating

I was left a message on my answerphone because a customer of mine had no central heating and asked me to attend the next day. He had told me that he could see that the pilot light was lit on his Baxi WM boiler and that the thermostat was turned up. He though it may be the pump as he had a pump seize before.

I attended in the morning, but unfortunately for myself the central heating had come on with the timer and had been working as it should be. The timer had switched off before I arrived and so I switched the heating on and the thermostat up. Everything was working with no obvious issues. I put the hot water on and tested the motorised valve to ensure that it was switching between heating and hot water as it should be. There appeared to be nothing wrong with the system.

The customer asked me to look at something unrelated which I did, and then went back to do a final test before leaving. On the final test I switched the heating on and the motorised valve began to move over but did not open fully enough to activate the micro-switch. I waited a few seconds longer but it still did not cause the boiler and pump to run. I put some pressure on the lever of the motorised valve and it moved further before activating the boiler an pump. I drained the system and replaced the motorised valve and everything has been working well since.

Disclaimer: The works described in this blog are a record of work undertaken and should not be taken as guaranteed to solve your problem. Work should only be carried out by persons qualified and competent to do so.

Main Combi HE Dripping Water

I received a call from a customer because they had water dripping slowly from the underneath of their Main Combi HE. Knowing these boilers quite well I had a goood idea of what the issue might be before I got there. When I got there I could see that the water was dripping from the left-hand side close to the front. I removed the front casing and dropped the controls casing down to reveal the inside of the boiler. Instantly I could see that the water was leaking from the differential pressure switch on the front of the diverter valve which is a common problem.

The diverter valves and differential pressure switches can also be found on other boilers (Baxi Combi 80, Baxi Combi 105, Potterton Performa and Alpha 240/280) and it is not uncommon for them to leak. The leak usually comes from where the pin exits the hex nut behind the micro-switch and worsens when the hot tap is run. I had an Interpart diapragm kit and so dis-assembled the differential pressure switch. Whenever I strip one of these down I always clean the pin with a bit of wire wool as there always appears to be some scale build up on the pin which could damage the seal on the new hex nut.

I reassembled the boiler and turned the water back on and tested that the pin was moving as it should be without leaking and that the boiler was behaving as it should be.

Disclaimer: The works described in this blog are a record of work undertaken and should not be taken as guaranteed to solve your problem. Work should only be carried out by persons qualified and competent to do so.

One Cold Radiator In Extension

I was asked to a look at a radiator recently that had not been working since the heating had been turned back on. The radiator was upstairs in the master bedroom which had been extended a few years previously and the radiator relocated. All the other radiators were nice and hot, and there was 16 other radiators. The customer had tried bleeding the radiator and to remove the head of the thermostatic radiator valve, but neither of these attempts got the radiator working successfully.

I removed the remainders of the head from the thermostatic radiator valve and pushed on the pin which was moving up and down perfectly. I then checked that the lockshield valve was fully open at the opposite end which it was. If there was an issue with balancing or circulation I would have expected one of the bigger radiators below to have been affected rather than an upstairs bedroom radiator.

I ensured the room thermostat was turned up fully and went around the house turning off all the other radiators. I checked back at the problem radiator and it was getting hotter to the pipe but the water was still not circulating through it. I looked in the airing cupboard and the system had two zone valves fitted and a bypass. The hot water was satisfied and the zone valve was closed accordingly, and I closed the bypass off. As soon as I turned off the bypass the full force of the pump pushed some air out of the pipework to the radiator and I heard it gurgle. Almost instantly the radiator was hot all over, and so I went around and turned all the other radiators and bypass back on.

The radiator continued to heat with the rest of the system up and running. I expect that over the summer air settles in the pipework to the radiator and prevents the circulation around that radiator. I expect when the radiator was relocated the installer used plastic pipe which because of the way it is often coiled never lies completely flat and leaves high points in the pipework for air to collect in.

Potterton Flamingo No Heating Downstairs

I received a call from a customer today that was worried about her heating. The radiators upstairs appeared to be working fine, but there was no heat at any of the radiators downstairs. It didn't matter that she turned the room thermostat right up they were not getting hot and when the boiler did come on it was only for a short period.

The programmer was set to constant for both heating and hot water, and the room thermostat was turned up high enough that the central heating should be on. Checking up in the airing cupboard the hot water was up to temperature and the motorised valve had moved over fully to the central heating position. The pump was also running although it didn't quite sound right. I thought that the cold feed may have been blocked but I felt the feed and vent and they both felt hot quite a way above where they tee in.

Pausing the rotation of the pump by moving the speed selector switch to a position between speeds didn't cause any gurgling which would suggest air or a lack of water preventing circulation. I also checked that the pump valves were both fully open. As everything seemed to be as it should I assumed that the pump was not spinning at the required velocity even though it did not look that old. I replaced the pump and switched the system back on and soon enough the radiators downstairs began to get warm.

Disclaimer: The works described in this blog are a record of work undertaken and should not be taken as guaranteed to solve your problem. Work should only be carried out by persons qualified and competent to do so.

Glowworm Flexicom CX Heating Not Working Properly

A friend of mine who is also a heating engineer asked me to look at a Glowworm Flexicom CX which a customer of his was having trouble with. He had serviced the boiler 6-7 months ago and the lady had called him back because it was not working correctly and hadn't been since he had serviced it apparently. During the summer one of the radiators had been getting hot when the hot water was run for extended periods and warm even when the hot water was run for shorter periods.

With the winter weather turning colder the lady began to use her heating and not all of the radiators were getting hot. Two of the three upstairs radiators were getting red hot, the other lukewarm. One of the radiators downstairs was getting lukewarm but the others were hardly getting warm. The boiler was getting up to temperature really quickly and then cutting off taking a while to cool down before relighting. When the status display was on it would run through the central heating status mode as normal eventually ending up on S7 the central heating pump over-run status. Then it would go to S97 where the boiler checks the water pressure sensor, and suggests you check the connection to the water pressure sensor and that the pump has not seized. Both of which appeared to be fine. The boiler flow was very hot when the boiler was running and the return was barely warm.

Another engineer had previously removed and cleaned out the water pressure sensor just after the boiler had been serviced and said there was a fair amount of debris fouling it. My friend also said that there was some debris when he drained one of the radiators. From this I assumed that the diverter valve may have been fouled with debris and not moving correctly between the heating and hot water positions. I drained the boiler and removed the diverter valve. To remove the diverter valve all three of the screws had to be removed fully before the diverter valve would come out, the bottom one was particularly tricky to access but managed to get it out with some needle nosed pliers.

After removing the diverter valve the remaining water in the boiler which leaked inside the boiler was really clean and there was no sign of any debris in the diverter valve. However it didn't look as if the motor was attached to the spindle of the diverter valve. I removed the motor from the diverter valve assembly and the spindle was free to move. I reconnected the spindle and fitted the motor back to the diverter valve assembly.
I then re-filled and tested the boiler. I ran the hot water and it was heating and modulating as it should to heat the water to an even temperature. I then switched the heating on and the motor moved the diverter valve in towards the back of the boiler and the connection to the spindle was visible through the hole in the diverter assembley close to the white plastic section. Opening the tap the motor pulled the spindle back outwards, and stayed there for a while after the tap has closed before the motor pushed the spindle back in.

I checked around all the radiators and they were all getting hot as they should be.

Potterton Promax Combi HE Low And High Pressure, Poor Hot Water

I was asked to service a Potterton Promax Combi HE as it had not been serviced since it had been installed. It was not that old but should have been serviced annually. When I arrived the customer had a list of issues with the boiler which also required investigation.

• The boiler keeps losing pressure
• The water pressure in the system keeps going into the red
• The hot water keeps going hot and cold
• One or two of the radiators were getting hot even though the heating was off

I looked over the boiler and asked if they had noticed any water leaks, which they hadn't. I looked at where the Pressure Relief Valve is terminated outside and could see that there was signs of it having let water out of the system. Having been leaking for while the PRV would require replacing as it was fouled with scale and debris from the system.

I topped up the water pressure to 1 1/2 bar and turned on the central heating system. It was not long before the water pressure in the system had risen and was close to the red. I turned off the heating and drained the pressure out of the heating system and checked the pressure in the pressure vessel. The pressure was low and with the drain point still open I increased the pressure in the vessel to the recommended amount through the schrader valve.

After setting the boiler back up I ran the hot tap and after running off the cold water in the leg of pipework it began to come through reasonably hot, and then cold, and then hot again and kept cycling like this without getting up to a satisfactory temperature. Watching the boiler I could see that it was rapidly getting up to temperature before cutting out, and was not transferring this heat to the hot water. When the boiler got up to it's maximum temperature it would send hot water out to the radiators explaining why a couple of the radiators had been hot at times through the summer. I removed the hot water plate heat exchanger and could see that it was quite badly blocked with debris and sludge from the system.

I replaced the PRV, plate heat exchanger and fitted a Adey Magnaclean filter to the system to protect the boiler from getting blocked again in the future. The system was only three years old and had been completely repiped with new radiators and treated with chemicals and yet surprisingly was in quite a bad state. I believe that some of the old pipework must have been re-used under the floor which was already fouled with scale and debris and not cleaned sufficiently when the new system was installed. Hopefully the Magnaclean will pick up the worst of the debris and keep it working as it should be.

Disclaimer: The works described in this blog are a record of work undertaken and should not be taken as guaranteed to solve your problem. Work should only be carried out by persons qualified and competent to do so.

Vaillant Turbomax Boiler Leaking

A customer of ours had a Vallaint Turbomax in a house that they recently moved into, which they had asked us to replace because of its age and inefficiency. They also wished for us to relocate the boiler to another area. The Vaillant Turbomax was of the VU/VUW range with the green control knobs. A week before we were going to replace it, a leak appeared from the underneath of the boiler.

The leak was only slow but needed immediate attention as the pressure was being lost from the system in less than a day. I could see that the water was coming from the right hand side of the boiler but could not see exactly as there was a panel on the underneath of the boiler. I opened the lower panel and dropped the controls down to see the diverter valve, etc. It was immediately obvious that the leak was coming from the automatic air vent, as there was water steadily appearing from the bleed pip.

I tried to screw the bleed pip down to stop the water from coming out of the cap but it would not seal. I dropped the pressure from the boiler and removed the top of the AAV. The float and mechanism of the AAV was fairly dirty and I may have been able to clean it up. However, I had a new AAV in the van which I dismantled and fitted to the boiler. This repair kept the boiler leak-free for another week and I was able to retrieve the AAV innards after replacing the boiler.

Disclaimer: The works described in this blog are a record of work undertaken and should not be taken as guaranteed to solve your problem. Work should only be carried out by persons qualified and competent to do so.